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Cfd Analysis of Convergent- Divergent Supersonic Nozzle
Fig. 1.6: Series of Rotor Blade.
1.3 Modeling of Nozzle and Turbine Blades as Partial Admission Case:
2D modeling of combined nozzle and series of 3 blades in a partial admission turbine rotor is carried
out by using the nozzle and blade profile generated data provided in Tables [1.1],[1.2],[1.3],[1.4]and [1.5]. As
analysis is to be carried out for different axial gap between rotor blades and nozzle, length of ordinate is fixed.
Rotor blades and nozzle with different axial gaps are modeled separately as shown in Figs. [1.7],[1.8] and [1.9]
for 3mm,4mm & 5mm axial gaps respectively.
Fig. 1.7: Solid Model as a Partial Admission Case of Nozzle and Rotor Blades with 3mm axial gap.
Fig 1.8: Solid Model as A Partial Admission Case of Nozzle and Rotor blades with 4mm axial gap.
Fig. 1.9: Solid Model as a Partial Admission Case of Nozzle and Rotor Blades with 5mm axial gap.
II. GRID GENERATION AND BOUNDARY CONDITIONS
The first step of the actual work is the geometry creation and then considers a certain domain of the
fluid in which the body is present under analysis. Then the volume occupied by the body as well as fluid is
divided into discrete cells called meshing Physical modeling is then defined i.e., equations of motion, no. of
phases in the flow, turbulence model etc. boundary conditions are defined now. This involves specifying the
fluid behavior and properties at the boundaries of the problem. Then the simulation is started and the equations
are solved iteratively as steady state or transient. Finally a post processor is used to view the results. These steps
are followed for both C-D nozzle and for combined nozzle and rotor blades.
2.1 Mesh Generation for 3D C-D Nozzle
The flow domain is required to be discretized to convert the partial differential equations in to series of
algebraic equations. This process is called grid generation. A 3D Model is created in GAMBIT as shown in
Fig.1.4. To generate the structured grid as shown in Fig.2.1 with hexahedral cells gambit is used. This mesh are
in good agreement with turbulence model gave good results, which otherwise didn’t match, with the
experimental ones.
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